1. Field
The following description relates to a 3-dimensional (3D) image display apparatus, and more particularly, to a 3D image display apparatus for displaying 3D images by applying a light field mechanism.
2. Description of the Related Art
Commercial 3D display apparatuses typically employ a mechanism in which an image depth is formed by displaying different images to each of the eyes of a viewer. However, this mechanism only provides binocular parallax information to a viewer and is unable to provide visual factors for monocular depth recognition, for example, focus adjustment and moving parallax. Therefore, a 3D image displayed according to this mechanism may present problems such as an “unnatural” image and eye fatigue.
Examples of techniques for displaying more “natural” 3D images that reduce eye fatigue include techniques for displaying 3D images by reproducing a spatio-angular distribution of light rays, that is, a light field. A light field refers to positional and directional distributions of light rays from an object.
When such a light field is optically reproduced on an arbitrary plane, a viewer located behind the plane experiences substantially the same light ray distribution as a real object, and thus a “natural” 3D image of the object may be seen. Techniques for reproducing a light field include a method of using a plurality of projectors and a directional diffuser or lens, a method of using a rotating mirror and a high-speed projector, a holographic stereogram, and the like.
According to the method of using a plurality of projectors, a light field is reproduced by emitting light from the plurality of projectors in different directions to produce projected images. Thus, a relatively large number of projectors is necessary. According to the method of using a rotating mirror, a light field is reproduced by emitting light in particular directions by using a high-speed projector and rotating the rotating mirror in synchronization with the projector to produce projected images. Here, since the rotating mirror is moved mechanically, the method generally cannot be applied to a flat panel type display apparatus.
A holographic stereogram is one of a plurality of holographic 3D displays. In a holographic stereogram, a hologram is divided into hogels, and each hogel reproduces a directional distribution of light rays at a corresponding position via diffraction. Here, each hogel displays a fringe pattern for reproducing the directional distribution of light rays. Since directions of light beams are changed through diffraction in the holographic stereogram, a pixel size required on a hologram surface is too small. Furthermore, when a motion picture is displayed, fringe patterns for each hogel are newly calculated per frame, and thus the amount of required calculations is excessive. The term ‘hogel’ refers to a holographic pixel containing 3D depth information. A pixel is formed of a 2-dimensional (2D) image unit.